<!DOCTYPE html>
<html lang="zh-CN" data-theme="light">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width,initial-scale=1" />
    <meta name="generator" content="VuePress 2.0.0-beta.38" />
    <meta name="theme" content="VuePress Theme Hope" />
    <meta property="og:url" content="https://javaguide.cn/java/basis/bigdecimal.html"><meta property="og:site_name" content="JavaGuide"><meta property="og:title" content="BigDecimal 详解"><meta property="og:type" content="article"><meta property="og:updated_time" content="2022-03-30T02:52:33.000Z"><meta property="og:locale" content="zh-CN"><meta property="article:tag" content="Java基础"><meta property="article:modified_time" content="2022-03-30T02:52:33.000Z"><script>var _hmt = _hmt || [];
      (function() {
        var hm = document.createElement("script");
        hm.src = "https://hm.baidu.com/hm.js?5dd2e8c97962d57b7b8fea1737c01743";
        var s = document.getElementsByTagName("script")[0]; 
        s.parentNode.insertBefore(hm, s);
      })();</script><link rel="stylesheet" href="//at.alicdn.com/t/font_2922463_99aa80ii7cf.css"><title>BigDecimal 详解 | JavaGuide</title><meta name="description" content="Java学习&&面试指南">
    <style>
      :root {
        --bg-color: #fff;
      }

      html[data-theme="dark"] {
        --bg-color: #1d2025;
      }

      html,
      body {
        background-color: var(--bg-color);
      }
    </style>
    <script>
      const userMode = localStorage.getItem("vuepress-theme-hope-scheme");
      const systemDarkMode =
        window.matchMedia &&
        window.matchMedia("(prefers-color-scheme: dark)").matches;

      if (userMode === "dark" || (userMode !== "light" && systemDarkMode)) {
        document.querySelector("html").setAttribute("data-theme", "dark");
      }
    </script>
    <link rel="stylesheet" href="/assets/style.aa943f56.css">
    <link rel="modulepreload" href="/assets/app.93341f6d.js"><link rel="modulepreload" href="/assets/bigdecimal.html.02034923.js"><link rel="modulepreload" href="/assets/bigdecimal.html.2cbdd8f8.js"><link rel="modulepreload" href="/assets/plugin-vue_export-helper.21dcd24c.js">
  </head>
  <body>
    <div id="app"><!--[--><!--[--><!--[--><span tabindex="-1"></span><a href="#main-content" class="skip-link sr-only">Skip to content</a><!--]--><div class="theme-container has-toc sidebar-open"><!--[--><header class="navbar"><button class="toggle-sidebar-button" title="Toggle Sidebar"><span class="icon"></span></button><a href="/" class="home-link"><img class="logo" src="/logo.png" alt="JavaGuide"><!----><span class="site-name hide-in-pad">JavaGuide</span><!--[--><!----><!--]--></a><nav class="nav-links" style=""><div class="nav-item hide-in-mobile"><a href="/home.html" class="nav-link" arialabel="面试指南"><i class="icon iconfont icon-java"></i>面试指南<!----></a></div><div class="nav-item hide-in-mobile"><a href="/zhuanlan/" class="nav-link" arialabel="优质专栏"><i class="icon iconfont icon-recommend"></i>优质专栏<!----></a></div><div class="nav-item hide-in-mobile"><a href="/open-source-project/" class="nav-link" arialabel="项目精选"><i class="icon iconfont icon-github"></i>项目精选<!----></a></div><div class="nav-item hide-in-mobile"><a href="/books/" class="nav-link" arialabel="书籍精选"><i class="icon iconfont icon-book"></i>书籍精选<!----></a></div><div class="nav-item hide-in-mobile"><a href="https://snailclimb.gitee.io/javaguide/#/" rel="noopener noreferrer" target="_blank" arialabel="旧版链接" class="nav-link"><i class="icon iconfont icon-java"></i>旧版链接<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!----></a></div><div class="nav-item hide-in-mobile"><a href="https://javaguide.cn/feed.json" rel="noopener noreferrer" target="_blank" arialabel="RSS订阅" class="nav-link"><i class="icon iconfont icon-rss"></i>RSS订阅<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!----></a></div><div class="nav-item hide-in-mobile"><a href="/about-the-author/" class="nav-link" arialabel="关于作者"><i class="icon iconfont icon-zuozhe"></i>关于作者<!----></a></div></nav><div class="nav-actions-wrapper"><!--[--><!----><!--]--><div class="nav-item"><!----></div><div class="nav-item"><a class="repo-link" href="https://github.com/Snailclimb/JavaGuide" target="_blank" rel="noopener noreferrer"><svg xmlns="http://www.w3.org/2000/svg" class="icon github-icon" viewbox="0 0 1024 1024" arialabelledby="github" style="width:1.25rem;height:1.25rem;vertical-align:middle;"><title id="github" lang="en">github icon</title><g fill="currentColor"><path d="M511.957 21.333C241.024 21.333 21.333 240.981 21.333 512c0 216.832 140.544 400.725 335.574 465.664 24.49 4.395 32.256-10.07 32.256-23.083 0-11.69.256-44.245 0-85.205-136.448 29.61-164.736-64.64-164.736-64.64-22.315-56.704-54.4-71.765-54.4-71.765-44.587-30.464 3.285-29.824 3.285-29.824 49.195 3.413 75.179 50.517 75.179 50.517 43.776 75.008 114.816 53.333 142.762 40.79 4.523-31.66 17.152-53.377 31.19-65.537-108.971-12.458-223.488-54.485-223.488-242.602 0-53.547 19.114-97.323 50.517-131.67-5.035-12.33-21.93-62.293 4.779-129.834 0 0 41.258-13.184 134.912 50.346a469.803 469.803 0 0 1 122.88-16.554c41.642.213 83.626 5.632 122.88 16.554 93.653-63.488 134.784-50.346 134.784-50.346 26.752 67.541 9.898 117.504 4.864 129.834 31.402 34.347 50.474 78.123 50.474 131.67 0 188.586-114.73 230.016-224.042 242.09 17.578 15.232 33.578 44.672 33.578 90.454v135.85c0 13.142 7.936 27.606 32.854 22.87C862.25 912.597 1002.667 728.747 1002.667 512c0-271.019-219.648-490.667-490.71-490.667z"></path></g></svg></a></div><div class="nav-item hide-in-mobile"><button id="appearance-switch"><svg xmlns="http://www.w3.org/2000/svg" class="icon auto-icon" viewbox="0 0 1024 1024" arialabelledby="auto" style="display:block;"><title id="auto" lang="en">auto icon</title><g fill="currentColor"><path d="M512 992C246.92 992 32 777.08 32 512S246.92 32 512 32s480 214.92 480 480-214.92 480-480 480zm0-840c-198.78 0-360 161.22-360 360 0 198.84 161.22 360 360 360s360-161.16 360-360c0-198.78-161.22-360-360-360zm0 660V212c165.72 0 300 134.34 300 300 0 165.72-134.28 300-300 300z"></path></g></svg><svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" viewbox="0 0 1024 1024" arialabelledby="dark" style="display:none;"><title id="dark" lang="en">dark icon</title><g fill="currentColor"><path d="M524.8 938.667h-4.267a439.893 439.893 0 0 1-313.173-134.4 446.293 446.293 0 0 1-11.093-597.334A432.213 432.213 0 0 1 366.933 90.027a42.667 42.667 0 0 1 45.227 9.386 42.667 42.667 0 0 1 10.24 42.667 358.4 358.4 0 0 0 82.773 375.893 361.387 361.387 0 0 0 376.747 82.774 42.667 42.667 0 0 1 54.187 55.04 433.493 433.493 0 0 1-99.84 154.88 438.613 438.613 0 0 1-311.467 128z"></path></g></svg><svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" viewbox="0 0 1024 1024" arialabelledby="light" style="display:none;"><title id="light" lang="en">light icon</title><g fill="currentColor"><path d="M952 552h-80a40 40 0 0 1 0-80h80a40 40 0 0 1 0 80zM801.88 280.08a41 41 0 0 1-57.96-57.96l57.96-58a41.04 41.04 0 0 1 58 58l-58 57.96zM512 752a240 240 0 1 1 0-480 240 240 0 0 1 0 480zm0-560a40 40 0 0 1-40-40V72a40 40 0 0 1 80 0v80a40 40 0 0 1-40 40zm-289.88 88.08-58-57.96a41.04 41.04 0 0 1 58-58l57.96 58a41 41 0 0 1-57.96 57.96zM192 512a40 40 0 0 1-40 40H72a40 40 0 0 1 0-80h80a40 40 0 0 1 40 40zm30.12 231.92a41 41 0 0 1 57.96 57.96l-57.96 58a41.04 41.04 0 0 1-58-58l58-57.96zM512 832a40 40 0 0 1 40 40v80a40 40 0 0 1-80 0v-80a40 40 0 0 1 40-40zm289.88-88.08 58 57.96a41.04 41.04 0 0 1-58 58l-57.96-58a41 41 0 0 1 57.96-57.96z"></path></g></svg></button></div><form class="search-box" role="search"><input type="search" placeholder="搜索" autocomplete="off" spellcheck="false" value><!----></form><button class="toggle-navbar-button" aria-label="Toggle Navbar" aria-expanded="false" aria-controls="nav-screen"><span class="button-container"><span class="button-top"></span><span class="button-middle"></span><span class="button-bottom"></span></span></button><!--[--><!----><!--]--></div></header><!----><!--]--><!----><div class="toggle-sidebar-wrapper"><span class="arrow left"></span></div><aside class="sidebar"><!--[--><!----><!--]--><ul class="sidebar-links"><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-mianshi"></i><span class="title">面试准备</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable active"><i class="icon iconfont icon-java"></i><span class="title">Java</span><span class="arrow down"></span></button><ul class="sidebar-links"><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable active"><i class="icon iconfont icon-basic"></i><span class="title">基础</span><span class="arrow down"></span></button><ul class="sidebar-links"><li><!--[--><a href="/java/basis/java-basic-questions-01.html" class="nav-link sidebar-link sidebar-page" arialabel="Java基础常见知识&amp;面试题总结(上)"><!---->Java基础常见知识&amp;面试题总结(上)<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/java/basis/java-basic-questions-02.html" class="nav-link sidebar-link sidebar-page" arialabel="Java基础常见知识&amp;面试题总结(中)"><!---->Java基础常见知识&amp;面试题总结(中)<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/java/basis/java-basic-questions-03.html" class="nav-link sidebar-link sidebar-page" arialabel="Java基础知识&amp;面试题总结(下)"><!---->Java基础知识&amp;面试题总结(下)<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable active"><i class="icon iconfont icon-important"></i><span class="title">重要知识点</span><span class="arrow down"></span></button><ul class="sidebar-links"><li><!--[--><a href="/java/basis/why-there-only-value-passing-in-java.html" class="nav-link sidebar-link sidebar-page" arialabel="为什么 Java 中只有值传递？"><!---->为什么 Java 中只有值传递？<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/java/basis/serialization.html" class="nav-link sidebar-link sidebar-page" arialabel="Java 序列化详解"><!---->Java 序列化详解<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/java/basis/reflection.html" class="nav-link sidebar-link sidebar-page" arialabel="反射机制详解"><!---->反射机制详解<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/java/basis/proxy.html" class="nav-link sidebar-link sidebar-page" arialabel="Java 代理模式详解"><!---->Java 代理模式详解<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/java/basis/io.html" class="nav-link sidebar-link sidebar-page" arialabel="IO 模型详解"><!---->IO 模型详解<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-current="page" href="/java/basis/bigdecimal.html" class="router-link-active router-link-exact-active nav-link active sidebar-link sidebar-page active" arialabel="BigDecimal 详解"><!---->BigDecimal 详解<!----></a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-介绍" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="BigDecimal 介绍"><!---->BigDecimal 介绍<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-的用处" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="BigDecimal 的用处"><!---->BigDecimal 的用处<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-常见方法" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="BigDecimal 常见方法"><!---->BigDecimal 常见方法<!----></a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#加减乘除" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="加减乘除"><!---->加减乘除<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#大小比较" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="大小比较"><!---->大小比较<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#保留几位小数" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="保留几位小数"><!---->保留几位小数<!----></a><ul class="sidebar-sub-headers"></ul></li></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-的使用注意事项" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="BigDecimal 的使用注意事项"><!---->BigDecimal 的使用注意事项<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-工具类分享" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="BigDecimal 工具类分享"><!---->BigDecimal 工具类分享<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/java/basis/bigdecimal.html#总结" class="router-link-active router-link-exact-active nav-link sidebar-link heading" arialabel="总结"><!---->总结<!----></a><ul class="sidebar-sub-headers"></ul></li></ul><!--]--></li></ul></section><!--]--></li></ul></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-container"></i><span class="title">容器</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-et-performance"></i><span class="title">并发编程</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-virtual_machine"></i><span class="title">JVM</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-features"></i><span class="title">新特性</span><span class="arrow right"></span></button><!----></section><!--]--></li></ul></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-computer"></i><span class="title">计算机基础</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-database"></i><span class="title">数据库</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-Tools"></i><span class="title">开发工具</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-xitongsheji"></i><span class="title">系统设计</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-distributed-network"></i><span class="title">分布式</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-et-performance"></i><span class="title">高性能</span><span class="arrow right"></span></button><!----></section><!--]--></li><li><!--[--><section class="sidebar-group"><button class="sidebar-heading clickable"><i class="icon iconfont icon-CalendarAvailability-1"></i><span class="title">高可用</span><span class="arrow right"></span></button><!----></section><!--]--></li></ul><!--[--><!----><!--]--></aside><!--[--><main class="page" id="main-content"><!----><nav class="breadcrumb disable"></nav><div class="page-title"><h1><!---->BigDecimal 详解</h1><div class="article-info"><span class="author-info" arialabel="作者🖊" isoriginal="false" pageview="false" color="false"><svg xmlns="http://www.w3.org/2000/svg" class="icon author-icon" viewbox="0 0 1024 1024" arialabelledby="author"><title id="author" lang="en">author icon</title><g fill="currentColor"><path d="M649.6 633.6c86.4-48 147.2-144 147.2-249.6 0-160-128-288-288-288s-288 128-288 288c0 108.8 57.6 201.6 147.2 249.6-121.6 48-214.4 153.6-240 288-3.2 9.6 0 19.2 6.4 25.6 3.2 9.6 12.8 12.8 22.4 12.8h704c9.6 0 19.2-3.2 25.6-12.8 6.4-6.4 9.6-16 6.4-25.6-25.6-134.4-121.6-240-243.2-288z"></path></g></svg><span><a class="author-item" href="https://javaguide.cn/" target="_blank" rel="noopener noreferrer">Guide</a></span><span property="author" content="Guide"></span></span><span class="category-info" arialabel="分类🌈" isoriginal="false" pageview="false"><svg xmlns="http://www.w3.org/2000/svg" class="icon category-icon" viewbox="0 0 1024 1024" arialabelledby="category"><title id="category" lang="en">category icon</title><g fill="currentColor"><path d="M148.41 106.992h282.176c22.263 0 40.31 18.048 40.31 40.31V429.48c0 22.263-18.047 40.31-40.31 40.31H148.41c-22.263 0-40.311-18.047-40.311-40.31V147.302c0-22.263 18.048-40.31 40.311-40.31zM147.556 553.478H429.73c22.263 0 40.311 18.048 40.311 40.31v282.176c0 22.263-18.048 40.312-40.31 40.312H147.555c-22.263 0-40.311-18.049-40.311-40.312V593.79c0-22.263 18.048-40.311 40.31-40.311zM593.927 106.992h282.176c22.263 0 40.31 18.048 40.31 40.31V429.48c0 22.263-18.047 40.31-40.31 40.31H593.927c-22.263 0-40.311-18.047-40.311-40.31V147.302c0-22.263 18.048-40.31 40.31-40.31zM730.22 920.502H623.926c-40.925 0-74.22-33.388-74.22-74.425V623.992c0-41.038 33.387-74.424 74.425-74.424h222.085c41.038 0 74.424 33.226 74.424 74.067v114.233c0 10.244-8.304 18.548-18.547 18.548s-18.548-8.304-18.548-18.548V623.635c0-20.388-16.746-36.974-37.33-36.974H624.13c-20.585 0-37.331 16.747-37.331 37.33v222.086c0 20.585 16.654 37.331 37.126 37.331H730.22c10.243 0 18.547 8.304 18.547 18.547 0 10.244-8.304 18.547-18.547 18.547z"></path></g></svg><ul class="categories-wrapper"><li class="category clickable" role="navigation">Java</li><meta property="articleSection" content="Java"></ul></span><span arialabel="标签🏷" isoriginal="false" pageview="false"><svg xmlns="http://www.w3.org/2000/svg" class="icon tag-icon" viewbox="0 0 1024 1024" arialabelledby="tag"><title id="tag" lang="en">tag icon</title><g fill="currentColor"><path d="M939.902 458.563L910.17 144.567c-1.507-16.272-14.465-29.13-30.737-30.737L565.438 84.098h-.402c-3.215 0-5.726 1.005-7.634 2.913l-470.39 470.39a10.004 10.004 0 000 14.164l365.423 365.424c1.909 1.908 4.42 2.913 7.132 2.913s5.223-1.005 7.132-2.913l470.39-470.39c2.01-2.11 3.014-5.023 2.813-8.036zm-240.067-72.121c-35.458 0-64.286-28.828-64.286-64.286s28.828-64.285 64.286-64.285 64.286 28.828 64.286 64.285-28.829 64.286-64.286 64.286z"></path></g></svg><ul class="tags-wrapper"><li class="tag clickable" role="navigation">Java基础</li></ul><meta property="keywords" content="Java基础"></span><span class="date-info" arialabel="写作日期📅" isoriginal="false" pageview="false" color="false"><svg xmlns="http://www.w3.org/2000/svg" class="icon calendar-icon" viewbox="0 0 1024 1024" arialabelledby="calendar"><title id="calendar" lang="en">calendar icon</title><g fill="currentColor"><path d="M716.4 110.137c0-18.753-14.72-33.473-33.472-33.473-18.753 0-33.473 14.72-33.473 33.473v33.473h66.993v-33.473zm-334.87 0c0-18.753-14.72-33.473-33.473-33.473s-33.52 14.72-33.52 33.473v33.473h66.993v-33.473zm468.81 33.52H716.4v100.465c0 18.753-14.72 33.473-33.472 33.473a33.145 33.145 0 01-33.473-33.473V143.657H381.53v100.465c0 18.753-14.72 33.473-33.473 33.473a33.145 33.145 0 01-33.473-33.473V143.657H180.6A134.314 134.314 0 0046.66 277.595v535.756A134.314 134.314 0 00180.6 947.289h669.74a134.36 134.36 0 00133.94-133.938V277.595a134.314 134.314 0 00-133.94-133.938zm33.473 267.877H147.126a33.145 33.145 0 01-33.473-33.473c0-18.752 14.72-33.473 33.473-33.473h736.687c18.752 0 33.472 14.72 33.472 33.473a33.145 33.145 0 01-33.472 33.473z"></path></g></svg><span>2021年12月13日</span><meta property="datePublished" content="2021-12-13T02:29:23.000Z"></span><!----><span class="words-info" arialabel="字数🔠" isoriginal="false" pageview="false" color="false"><svg xmlns="http://www.w3.org/2000/svg" class="icon word-icon" viewbox="0 0 1024 1024" arialabelledby="word"><title id="word" lang="en">word icon</title><g fill="currentColor"><path d="M518.217 432.64V73.143A73.143 73.143 0 01603.43 1.097a512 512 0 01419.474 419.474 73.143 73.143 0 01-72.046 85.212H591.36a73.143 73.143 0 01-73.143-73.143z"></path><path d="M493.714 566.857h340.297a73.143 73.143 0 0173.143 85.577A457.143 457.143 0 11371.566 117.76a73.143 73.143 0 0185.577 73.143v339.383a36.571 36.571 0 0036.571 36.571z"></path></g></svg><span>约 2041 字</span><meta property="wordCount" content="2041"></span></div><hr></div><div class="toc-place-holder"><aside id="toc-list"><div class="toc-header">此页内容</div><div class="toc-wrapper"><ul class="toc-list"><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-介绍" class="router-link-active router-link-exact-active toc-link level2">BigDecimal 介绍</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-的用处" class="router-link-active router-link-exact-active toc-link level2">BigDecimal 的用处</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-常见方法" class="router-link-active router-link-exact-active toc-link level2">BigDecimal 常见方法</a></li><ul class="toc-list"><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#加减乘除" class="router-link-active router-link-exact-active toc-link level3">加减乘除</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#大小比较" class="router-link-active router-link-exact-active toc-link level3">大小比较</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#保留几位小数" class="router-link-active router-link-exact-active toc-link level3">保留几位小数</a></li><!----><!--]--></ul><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-的使用注意事项" class="router-link-active router-link-exact-active toc-link level2">BigDecimal 的使用注意事项</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#bigdecimal-工具类分享" class="router-link-active router-link-exact-active toc-link level2">BigDecimal 工具类分享</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/java/basis/bigdecimal.html#总结" class="router-link-active router-link-exact-active toc-link level2">总结</a></li><!----><!--]--></ul></div></aside></div><!----><div class="theme-hope-content"><!--[--><p>《阿里巴巴 Java 开发手册》中提到：“为了避免精度丢失，可以使用 <code>BigDecimal</code> 来进行浮点数的运算”。</p><p>这篇文章，我就简单解释一下浮点数运算出现精度丢失的原因以及 <code>BigDecimal</code> 的常见用法，希望对大家有帮助！</p><h2 id="bigdecimal-介绍" tabindex="-1"><a class="header-anchor" href="#bigdecimal-介绍" aria-hidden="true">#</a> BigDecimal 介绍</h2><p><code>BigDecimal</code> 可以实现对浮点数的运算，不会造成精度丢失。通常情况下，大部分需要浮点数精确运算结果的业务场景（比如涉及到钱的场景）都是通过 <code>BigDecimal</code> 来做的。</p><p>纳尼，浮点数的运算竟然还会有精度丢失的风险吗？确实会！</p><p>示例代码：</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">float</span> a <span class="token operator">=</span> <span class="token number">2.0f</span> <span class="token operator">-</span> <span class="token number">1.9f</span><span class="token punctuation">;</span>
<span class="token keyword">float</span> b <span class="token operator">=</span> <span class="token number">1.8f</span> <span class="token operator">-</span> <span class="token number">1.7f</span><span class="token punctuation">;</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 0.100000024</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 0.099999905</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a <span class="token operator">==</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// false</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p><strong>为什么浮点数 <code>float</code> 或 <code>double</code> 运算的时候会有精度丢失的风险呢？</strong></p><p>这个和计算机保存浮点数的机制有很大关系。我们知道计算机是二进制的，而且计算机在表示一个数字时，宽度是有限的，无限循环的小数存储在计算机时，只能被截断，所以就会导致小数精度发生损失的情况。这也就是解释了为什么浮点数没有办法用二进制精确表示。</p><p>就比如说十进制下的 0.2 就没办法精确转换成二进制小数：</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token comment">// 0.2 转换为二进制数的过程为，不断乘以 2，直到不存在小数为止，</span>
<span class="token comment">// 在这个计算过程中，得到的整数部分从上到下排列就是二进制的结果。</span>
<span class="token number">0.2</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">=</span> <span class="token number">0.4</span> <span class="token operator">-&gt;</span> <span class="token number">0</span>
<span class="token number">0.4</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">=</span> <span class="token number">0.8</span> <span class="token operator">-&gt;</span> <span class="token number">0</span>
<span class="token number">0.8</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">=</span> <span class="token number">1.6</span> <span class="token operator">-&gt;</span> <span class="token number">1</span>
<span class="token number">0.6</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">=</span> <span class="token number">1.2</span> <span class="token operator">-&gt;</span> <span class="token number">1</span>
<span class="token number">0.2</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">=</span> <span class="token number">0.4</span> <span class="token operator">-&gt;</span> <span class="token number">0</span>（发生循环）
<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><p>关于浮点数的更多内容，建议看一下<a href="http://kaito-kidd.com/2018/08/08/computer-system-float-point/" target="_blank" rel="noopener noreferrer">计算机系统基础（四）浮点数<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span></a>这篇文章。</p><h2 id="bigdecimal-的用处" tabindex="-1"><a class="header-anchor" href="#bigdecimal-的用处" aria-hidden="true">#</a> BigDecimal 的用处</h2><p>《阿里巴巴 Java 开发手册》中提到：<strong>浮点数之间的等值判断，基本数据类型不能用==来比较，包装数据类型不能用 equals 来判断。</strong></p><p><img src="https://guide-blog-images.oss-cn-shenzhen.aliyuncs.com/javaguide/image-20211213101646884.png" alt="" loading="lazy"></p><p>具体原因我们在上面已经详细介绍了，这里就不多提了，我们下面直接上实例：</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">float</span> a <span class="token operator">=</span> <span class="token number">1.0f</span> <span class="token operator">-</span> <span class="token number">0.9f</span><span class="token punctuation">;</span>
<span class="token keyword">float</span> b <span class="token operator">=</span> <span class="token number">0.9f</span> <span class="token operator">-</span> <span class="token number">0.8f</span><span class="token punctuation">;</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 0.100000024</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 0.099999964</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a <span class="token operator">==</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// false</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>从输出结果就可以看出发生精度丢失的问题。</p><p>想要解决这个问题也很简单，直接使用 <code>BigDecimal</code> 来定义浮点数的值，再进行浮点数的运算操作即可。</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token class-name">BigDecimal</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;1.0&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">BigDecimal</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;0.9&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">BigDecimal</span> c <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;0.8&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token class-name">BigDecimal</span> x <span class="token operator">=</span> a<span class="token punctuation">.</span><span class="token function">subtract</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">BigDecimal</span> y <span class="token operator">=</span> b<span class="token punctuation">.</span><span class="token function">subtract</span><span class="token punctuation">(</span>c<span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">/* 0.1 */</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>y<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">/* 0.1 */</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token class-name">Objects</span><span class="token punctuation">.</span><span class="token function">equals</span><span class="token punctuation">(</span>x<span class="token punctuation">,</span> y<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">/* true */</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><h2 id="bigdecimal-常见方法" tabindex="-1"><a class="header-anchor" href="#bigdecimal-常见方法" aria-hidden="true">#</a> BigDecimal 常见方法</h2><h3 id="加减乘除" tabindex="-1"><a class="header-anchor" href="#加减乘除" aria-hidden="true">#</a> 加减乘除</h3><p><code>add</code> 方法用于将两个 <code>BigDecimal</code> 对象相加，<code>subtract</code> 方法用于将两个 <code>BigDecimal</code> 对象相减。<code>multiply</code> 方法用于将两个 <code>BigDecimal</code> 对象相乘，<code>divide</code> 方法用于将两个 <code>BigDecimal</code> 对象相除。</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token class-name">BigDecimal</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;1.0&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">BigDecimal</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;0.9&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 1.9</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">subtract</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 0.1</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">multiply</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 0.90</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">divide</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 无法除尽，抛出 ArithmeticException 异常</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">divide</span><span class="token punctuation">(</span>b<span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token class-name">RoundingMode</span><span class="token punctuation">.</span>HALF_UP<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 1.11</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><p>这里需要注意的是，在我们使用 <code>divide</code> 方法的时候尽量使用 3 个参数版本，并且<code>RoundingMode</code> 不要选择 <code>UNNECESSARY</code>，否则很可能会遇到 <code>ArithmeticException</code>（无法除尽出现无限循环小数的时候），其中 <code>scale</code> 表示要保留几位小数，<code>roundingMode</code> 代表保留规则。</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token class-name">BigDecimal</span> <span class="token function">divide</span><span class="token punctuation">(</span><span class="token class-name">BigDecimal</span> divisor<span class="token punctuation">,</span> <span class="token keyword">int</span> scale<span class="token punctuation">,</span> <span class="token class-name">RoundingMode</span> roundingMode<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token function">divide</span><span class="token punctuation">(</span>divisor<span class="token punctuation">,</span> scale<span class="token punctuation">,</span> roundingMode<span class="token punctuation">.</span>oldMode<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><p>保留规则非常多，这里列举几种:</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">enum</span> <span class="token class-name">RoundingMode</span> <span class="token punctuation">{</span>
   <span class="token comment">// 2.5 -&gt; 3 , 1.6 -&gt; 2</span>
   <span class="token comment">// -1.6 -&gt; -2 , -2.5 -&gt; -3</span>
			 <span class="token function">UP</span><span class="token punctuation">(</span><span class="token class-name">BigDecimal</span><span class="token punctuation">.</span>ROUND_UP<span class="token punctuation">)</span><span class="token punctuation">,</span>
   <span class="token comment">// 2.5 -&gt; 2 , 1.6 -&gt; 1</span>
   <span class="token comment">// -1.6 -&gt; -1 , -2.5 -&gt; -2</span>
			 <span class="token function">DOWN</span><span class="token punctuation">(</span><span class="token class-name">BigDecimal</span><span class="token punctuation">.</span>ROUND_DOWN<span class="token punctuation">)</span><span class="token punctuation">,</span>
			 <span class="token comment">// 2.5 -&gt; 3 , 1.6 -&gt; 2</span>
   <span class="token comment">// -1.6 -&gt; -1 , -2.5 -&gt; -2</span>
			 <span class="token function">CEILING</span><span class="token punctuation">(</span><span class="token class-name">BigDecimal</span><span class="token punctuation">.</span>ROUND_CEILING<span class="token punctuation">)</span><span class="token punctuation">,</span>
			 <span class="token comment">// 2.5 -&gt; 2 , 1.6 -&gt; 1</span>
   <span class="token comment">// -1.6 -&gt; -2 , -2.5 -&gt; -3</span>
			 <span class="token function">FLOOR</span><span class="token punctuation">(</span><span class="token class-name">BigDecimal</span><span class="token punctuation">.</span>ROUND_FLOOR<span class="token punctuation">)</span><span class="token punctuation">,</span>
   	<span class="token comment">// 2.5 -&gt; 3 , 1.6 -&gt; 2</span>
   <span class="token comment">// -1.6 -&gt; -2 , -2.5 -&gt; -3</span>
			 <span class="token function">HALF_UP</span><span class="token punctuation">(</span><span class="token class-name">BigDecimal</span><span class="token punctuation">.</span>ROUND_HALF_UP<span class="token punctuation">)</span><span class="token punctuation">,</span>
   <span class="token comment">//......</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br></div></div><h3 id="大小比较" tabindex="-1"><a class="header-anchor" href="#大小比较" aria-hidden="true">#</a> 大小比较</h3><p><code>a.compareTo(b)</code> : 返回 -1 表示 <code>a</code> 小于 <code>b</code>，0 表示 <code>a</code> 等于 <code>b</code> ， 1 表示 <code>a</code> 大于 <code>b</code>。</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token class-name">BigDecimal</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;1.0&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">BigDecimal</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;0.9&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span><span class="token function">compareTo</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 1</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><h3 id="保留几位小数" tabindex="-1"><a class="header-anchor" href="#保留几位小数" aria-hidden="true">#</a> 保留几位小数</h3><p>通过 <code>setScale</code>方法设置保留几位小数以及保留规则。保留规则有挺多种，不需要记，IDEA 会提示。</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token class-name">BigDecimal</span> m <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;1.255433&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">BigDecimal</span> n <span class="token operator">=</span> m<span class="token punctuation">.</span><span class="token function">setScale</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token class-name">RoundingMode</span><span class="token punctuation">.</span>HALF_DOWN<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>n<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">// 1.255</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><h2 id="bigdecimal-的使用注意事项" tabindex="-1"><a class="header-anchor" href="#bigdecimal-的使用注意事项" aria-hidden="true">#</a> BigDecimal 的使用注意事项</h2><p>注意：我们在使用 <code>BigDecimal</code> 时，为了防止精度丢失，推荐使用它的<code>BigDecimal(String val)</code>构造方法或者 <code>BigDecimal.valueOf(double val)</code> 静态方法来创建对象。</p><p>《阿里巴巴 Java 开发手册》对这部分内容也有提到，如下图所示。</p><p><img src="https://guide-blog-images.oss-cn-shenzhen.aliyuncs.com/javaguide/image-20211213102222601.png" alt="" loading="lazy"></p><h2 id="bigdecimal-工具类分享" tabindex="-1"><a class="header-anchor" href="#bigdecimal-工具类分享" aria-hidden="true">#</a> BigDecimal 工具类分享</h2><p>网上有一个使用人数比较多的 <code>BigDecimal</code> 工具类，提供了多个静态方法来简化 <code>BigDecimal</code> 的操作。</p><p>我对其进行了简单改进，分享一下源码：</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">import</span> <span class="token namespace">java<span class="token punctuation">.</span>math<span class="token punctuation">.</span></span><span class="token class-name">BigDecimal</span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token namespace">java<span class="token punctuation">.</span>math<span class="token punctuation">.</span></span><span class="token class-name">RoundingMode</span><span class="token punctuation">;</span>

<span class="token doc-comment comment">/**
 * 简化BigDecimal计算的小工具类
 */</span>
<span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">BigDecimalUtil</span> <span class="token punctuation">{</span>

    <span class="token doc-comment comment">/**
     * 默认除法运算精度
     */</span>
    <span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token keyword">int</span> DEF_DIV_SCALE <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span>

    <span class="token keyword">private</span> <span class="token class-name">BigDecimalUtil</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供精确的加法运算。
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span> 被加数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span> 加数
     * <span class="token keyword">@return</span> 两个参数的和
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">add</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b1 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v1<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> b2 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v2<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b1<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>b2<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">doubleValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供精确的减法运算。
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span> 被减数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span> 减数
     * <span class="token keyword">@return</span> 两个参数的差
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">subtract</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b1 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v1<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> b2 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v2<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b1<span class="token punctuation">.</span><span class="token function">subtract</span><span class="token punctuation">(</span>b2<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">doubleValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供精确的乘法运算。
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span> 被乘数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span> 乘数
     * <span class="token keyword">@return</span> 两个参数的积
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">multiply</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b1 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v1<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> b2 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v2<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b1<span class="token punctuation">.</span><span class="token function">multiply</span><span class="token punctuation">(</span>b2<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">doubleValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供（相对）精确的除法运算，当发生除不尽的情况时，精确到
     * 小数点以后10位，以后的数字四舍五入。
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span> 被除数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span> 除数
     * <span class="token keyword">@return</span> 两个参数的商
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">divide</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">return</span> <span class="token function">divide</span><span class="token punctuation">(</span>v1<span class="token punctuation">,</span> v2<span class="token punctuation">,</span> DEF_DIV_SCALE<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供（相对）精确的除法运算。当发生除不尽的情况时，由scale参数指
     * 定精度，以后的数字四舍五入。
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span>    被除数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span>    除数
     * <span class="token keyword">@param</span> <span class="token parameter">scale</span> 表示表示需要精确到小数点以后几位。
     * <span class="token keyword">@return</span> 两个参数的商
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">divide</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">,</span> <span class="token keyword">int</span> scale<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">if</span> <span class="token punctuation">(</span>scale <span class="token operator">&lt;</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span>
                    <span class="token string">&quot;The scale must be a positive integer or zero&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
        <span class="token class-name">BigDecimal</span> b1 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v1<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> b2 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v2<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b1<span class="token punctuation">.</span><span class="token function">divide</span><span class="token punctuation">(</span>b2<span class="token punctuation">,</span> scale<span class="token punctuation">,</span> <span class="token class-name">RoundingMode</span><span class="token punctuation">.</span>HALF_UP<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">doubleValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供精确的小数位四舍五入处理。
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v</span>     需要四舍五入的数字
     * <span class="token keyword">@param</span> <span class="token parameter">scale</span> 小数点后保留几位
     * <span class="token keyword">@return</span> 四舍五入后的结果
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">round</span><span class="token punctuation">(</span><span class="token keyword">double</span> v<span class="token punctuation">,</span> <span class="token keyword">int</span> scale<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">if</span> <span class="token punctuation">(</span>scale <span class="token operator">&lt;</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span>
                    <span class="token string">&quot;The scale must be a positive integer or zero&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
        <span class="token class-name">BigDecimal</span> b <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> one <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span><span class="token string">&quot;1&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b<span class="token punctuation">.</span><span class="token function">divide</span><span class="token punctuation">(</span>one<span class="token punctuation">,</span> scale<span class="token punctuation">,</span> <span class="token class-name">RoundingMode</span><span class="token punctuation">.</span>HALF_UP<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">doubleValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供精确的类型转换(Float)
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v</span> 需要被转换的数字
     * <span class="token keyword">@return</span> 返回转换结果
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">float</span> <span class="token function">convertToFloat</span><span class="token punctuation">(</span><span class="token keyword">double</span> v<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b<span class="token punctuation">.</span><span class="token function">floatValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供精确的类型转换(Int)不进行四舍五入
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v</span> 需要被转换的数字
     * <span class="token keyword">@return</span> 返回转换结果
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">int</span> <span class="token function">convertsToInt</span><span class="token punctuation">(</span><span class="token keyword">double</span> v<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b<span class="token punctuation">.</span><span class="token function">intValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 提供精确的类型转换(Long)
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v</span> 需要被转换的数字
     * <span class="token keyword">@return</span> 返回转换结果
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">long</span> <span class="token function">convertsToLong</span><span class="token punctuation">(</span><span class="token keyword">double</span> v<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span>v<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b<span class="token punctuation">.</span><span class="token function">longValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 返回两个数中大的一个值
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span> 需要被对比的第一个数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span> 需要被对比的第二个数
     * <span class="token keyword">@return</span> 返回两个数中大的一个值
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">returnMax</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span>v1<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> b2 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span>v2<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b1<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span>b2<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">doubleValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 返回两个数中小的一个值
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span> 需要被对比的第一个数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span> 需要被对比的第二个数
     * <span class="token keyword">@return</span> 返回两个数中小的一个值
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">returnMin</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span>v1<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> b2 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">(</span>v2<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b1<span class="token punctuation">.</span><span class="token function">min</span><span class="token punctuation">(</span>b2<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">doubleValue</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token doc-comment comment">/**
     * 精确对比两个数字
     *
     * <span class="token keyword">@param</span> <span class="token parameter">v1</span> 需要被对比的第一个数
     * <span class="token keyword">@param</span> <span class="token parameter">v2</span> 需要被对比的第二个数
     * <span class="token keyword">@return</span> 如果两个数一样则返回0，如果第一个数比第二个数大则返回1，反之返回-1
     */</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">int</span> <span class="token function">compareTo</span><span class="token punctuation">(</span><span class="token keyword">double</span> v1<span class="token punctuation">,</span> <span class="token keyword">double</span> v2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token class-name">BigDecimal</span> b1 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v1<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token class-name">BigDecimal</span> b2 <span class="token operator">=</span> <span class="token class-name">BigDecimal</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>v2<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">return</span> b1<span class="token punctuation">.</span><span class="token function">compareTo</span><span class="token punctuation">(</span>b2<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br><span class="line-number">57</span><br><span class="line-number">58</span><br><span class="line-number">59</span><br><span class="line-number">60</span><br><span class="line-number">61</span><br><span class="line-number">62</span><br><span class="line-number">63</span><br><span class="line-number">64</span><br><span class="line-number">65</span><br><span class="line-number">66</span><br><span class="line-number">67</span><br><span class="line-number">68</span><br><span class="line-number">69</span><br><span class="line-number">70</span><br><span class="line-number">71</span><br><span class="line-number">72</span><br><span class="line-number">73</span><br><span class="line-number">74</span><br><span class="line-number">75</span><br><span class="line-number">76</span><br><span class="line-number">77</span><br><span class="line-number">78</span><br><span class="line-number">79</span><br><span class="line-number">80</span><br><span class="line-number">81</span><br><span class="line-number">82</span><br><span class="line-number">83</span><br><span class="line-number">84</span><br><span class="line-number">85</span><br><span class="line-number">86</span><br><span class="line-number">87</span><br><span class="line-number">88</span><br><span class="line-number">89</span><br><span class="line-number">90</span><br><span class="line-number">91</span><br><span class="line-number">92</span><br><span class="line-number">93</span><br><span class="line-number">94</span><br><span class="line-number">95</span><br><span class="line-number">96</span><br><span class="line-number">97</span><br><span class="line-number">98</span><br><span class="line-number">99</span><br><span class="line-number">100</span><br><span class="line-number">101</span><br><span class="line-number">102</span><br><span class="line-number">103</span><br><span class="line-number">104</span><br><span class="line-number">105</span><br><span class="line-number">106</span><br><span class="line-number">107</span><br><span class="line-number">108</span><br><span class="line-number">109</span><br><span class="line-number">110</span><br><span class="line-number">111</span><br><span class="line-number">112</span><br><span class="line-number">113</span><br><span class="line-number">114</span><br><span class="line-number">115</span><br><span class="line-number">116</span><br><span class="line-number">117</span><br><span class="line-number">118</span><br><span class="line-number">119</span><br><span class="line-number">120</span><br><span class="line-number">121</span><br><span class="line-number">122</span><br><span class="line-number">123</span><br><span class="line-number">124</span><br><span class="line-number">125</span><br><span class="line-number">126</span><br><span class="line-number">127</span><br><span class="line-number">128</span><br><span class="line-number">129</span><br><span class="line-number">130</span><br><span class="line-number">131</span><br><span class="line-number">132</span><br><span class="line-number">133</span><br><span class="line-number">134</span><br><span class="line-number">135</span><br><span class="line-number">136</span><br><span class="line-number">137</span><br><span class="line-number">138</span><br><span class="line-number">139</span><br><span class="line-number">140</span><br><span class="line-number">141</span><br><span class="line-number">142</span><br><span class="line-number">143</span><br><span class="line-number">144</span><br><span class="line-number">145</span><br><span class="line-number">146</span><br><span class="line-number">147</span><br><span class="line-number">148</span><br><span class="line-number">149</span><br><span class="line-number">150</span><br><span class="line-number">151</span><br><span class="line-number">152</span><br><span class="line-number">153</span><br><span class="line-number">154</span><br><span class="line-number">155</span><br><span class="line-number">156</span><br><span class="line-number">157</span><br><span class="line-number">158</span><br><span class="line-number">159</span><br><span class="line-number">160</span><br><span class="line-number">161</span><br><span class="line-number">162</span><br><span class="line-number">163</span><br><span class="line-number">164</span><br><span class="line-number">165</span><br><span class="line-number">166</span><br><span class="line-number">167</span><br><span class="line-number">168</span><br><span class="line-number">169</span><br><span class="line-number">170</span><br><span class="line-number">171</span><br><span class="line-number">172</span><br><span class="line-number">173</span><br><span class="line-number">174</span><br><span class="line-number">175</span><br><span class="line-number">176</span><br></div></div><h2 id="总结" tabindex="-1"><a class="header-anchor" href="#总结" aria-hidden="true">#</a> 总结</h2><p>浮点数没有办法用二进制精确表示，因此存在精度丢失的风险。</p><p>不过，Java 提供了<code>BigDecimal</code> 来操作浮点数。<code>BigDecimal</code> 的实现利用到了 <code>BigInteger</code> （用来操作大整数）, 所不同的是 <code>BigDecimal</code> 加入了小数位的概念。</p><!--]--></div><!----><footer class="page-meta"><div class="meta-item edit-link"><a href="https://github.com/Snailclimb/JavaGuide/edit/main/docs/java/basis/bigdecimal.md" rel="noopener noreferrer" target="_blank" arialabel="编辑此页" class="nav-link label"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewbox="0 0 1024 1024" arialabelledby="edit"><title id="edit" lang="en">edit icon</title><g fill="currentColor"><path d="M430.818 653.65a60.46 60.46 0 0 1-50.96-93.281l71.69-114.012 7.773-10.365L816.038 80.138A60.46 60.46 0 0 1 859.225 62a60.46 60.46 0 0 1 43.186 18.138l43.186 43.186a60.46 60.46 0 0 1 0 86.373L588.879 565.55l-8.637 8.637-117.466 68.234a60.46 60.46 0 0 1-31.958 11.229z"></path><path d="M728.802 962H252.891A190.883 190.883 0 0 1 62.008 771.98V296.934a190.883 190.883 0 0 1 190.883-192.61h267.754a60.46 60.46 0 0 1 0 120.92H252.891a69.962 69.962 0 0 0-69.098 69.099V771.98a69.962 69.962 0 0 0 69.098 69.098h475.911A69.962 69.962 0 0 0 797.9 771.98V503.363a60.46 60.46 0 1 1 120.922 0V771.98A190.883 190.883 0 0 1 728.802 962z"></path></g></svg><!--]-->编辑此页<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!----></a></div><div class="meta-item update-time"><span class="label">上次编辑于: </span><span class="info">2022/3/30 10:52:33</span></div><div class="meta-item contributors"><span class="label">贡献者: </span><!--[--><!--[--><span class="contributor" title="email: koushuangbwcx@163.com">guide</span><!--]--><!--]--></div></footer><nav class="page-nav"><a href="/java/basis/io.html" class="nav-link prev" arialabel="IO 模型详解"><div class="hint"><span class="arrow left"></span>上一页</div><div class="link"><!---->IO 模型详解</div></a><!----></nav><!----><!----></main><!--]--><footer class="footer-wrapper"><div class="footer"><a href="https://beian.miit.gov.cn/" target="_blank">鄂ICP备2020015769号-1</a></div><div class="copyright">Copyright © 2022 Guide</div></footer></div><!--]--><!----><!--]--></div>
    <script type="module" src="/assets/app.93341f6d.js" defer></script>
  </body>
</html>
